Double-runner spiral pump



July l, 1930. F. MOODY 1,769,886

DOUBLE RUNNER SPIRAL PUMP Filed April 7, 192e 35% 14M @lbtowwl/bAoppositely directed impellersclosely spacedV Patented July 1, 1930narran states earner ostina LEWIS FERRYMOODY, OF PHILADELPHIA,PENNSYLVANIA DOUBLE-RUNNER SPIRAL P'UlYIIP Application filed April 7,

Thisinvention relates to hydraulic pumps, and particularly to high-speedpropeller type pumps of the double or twin type.'

Onecof the/objects of this invention is to provide a pump containing twoimpellers of 'opposite hand, to rform a. pump of high speciiic speed,high efficiency, and of compact design, in which the iiow shall proceedwithout being subjected to contact with excessive areas of confiningwalls in the region ofA the 4highvelocity flow in order to avoidexcessive lossof head1 due to. surface resistance, whileV at thel sameV.time .the flow shall follow smoothlines without losses dueto eddies ordisturbances. Another object is to provide a pump of this character.which is ,simple in construction, small in act-ual dimensions, ofv

lightweight, and formedof few parts. i'

5A.ffurther object of vtheinvention is to provide a pump of thischaracter with its toeach other and without unnecessary andobjectionable directing surfaces interposed between the impellers Atoprovide forced guidance ofthe discharge from the impellers into theoutwardi'direction. v

vFurther objects and advantages of the Yinvention will be apparent byreference .to the following specication and drawings in which"` 4 Fig. 1is a sectional View on line 1-1 of Fig. 2, and

Fig. 2 is a vertical sectional view online 2-2`of Fig.V 1.k

In the specific embodiment of the inven- V tien illustrated 10'represents' a central volute ,outlet casing, 11 and 12 similar intakecasings, and 18 and lvrepresent similaraxial flow propellertypeimpellers having unshrouded blades mounted upon a centralV shaft 15.rEhe intake casings-11 and 12 are each formed with an intake passage 16,

1T leading to the inclined guide vanesrlS'l A'lheintake passages may beof..

and 19. the single or double volute form and serve to direct the waterfrom a generalradial direction into an axial direction to passages20-20. From these points the passage walls turn outwardly. The impellers13 and 14 are keyed or otherwise secured on the shaft 15Y 19%.. SerialNo. 100,207.

and are held'against lateral displacement by j l y means of collers21and 22 bolted or otherwise secured to the shaft 15. The collars 21 and22'serve to hold the impeller against a straight central cylindricalspacer in the form ofa sleeve 23. Collar 21 may be in- Inpracticethejwater entering the passages L 1G and 17 is .given the desireddegreeof whirl by entrance vanes 18and 19, and thence passing throughthe passages 20-20 is delivered to the impellers 13 and 14 in the formof solid whirling streams, the water from both iinlpellers oining toforma single continuous rotating mass of water.y Issuing from the im pellersi the ilow passes outwardly into Vthe outlet 10 and proceedingfromv theimpeller 7v the water is underfpressure and will follow naturalstreamlines to turn without the necessity ofany enlarged central core orden flector between them. The whirling flow in leaving the impellers andpassing outwardly u into the casinglO .will pass .from points near theaxis toicontinually greater and greater radial distances .from .theaxis'a-nd will be thereby decelerated, according to the principle ofconstancy of moment of momentum, according to which the linear velocityof rotation of fluid, contained within the free space is inverselyproportional to its radial distance from the axis.

Thecasing will, in general, be designed to conform to thevelocitydetermined by this principle and to provide continuous deceleiation of velocity as the water flows through the casing. Y The casing 10is formed wit-h a throat opening of reduced width between the opposingwallsqat a point a short dist-ance outside of the vimpeller tips inorder to hold the` streams of water together and to avoid any tendencyof the natural lines of flow to part from-the walls. A. casing throatmeasured in an axial direction will usually be less than aboutthree-fourths of the impeller diameter in order to conform to the How.Outside of this throat section where the outward 5 radial components ofvelocity become suffimay be easily assembled, as will be seen by an inection of the drawings. The casngs will or arily be in t-wo piecesseparable on a horizontal plane containing the axis to facilitateremoval of the shaft and impellers.

umps of the spiral type to which this invenA ion apslies the recovery ofthe energy of thewater ischarged from the impellers is unimportant partof the hydraulic action of the pump, since this ener represents a valueiu'high'speed umps o this type which is lar' compare to the net headagainst which the pump is delivering.

J "flhe entranceguide-vanes 18, 19 are formed sito lguidethe water in adirection of rotation ab u tithe impeller axis, this initial rotation ifor the entering water being in the same sense asithe rotation of theimpeller. For pumps of special `characteristics, theguide-vanes 18,

19 may be omitted, the water then being ermi to take up its naturaldegree of w irl without *forced guidance, the omission of theguida-vanas producinY in eneral a less rapidly falling curve Aofthearelatively to discharge.

The impellers are of high specific eed, havingblades which when cut bycylin rical surfaces 'about the axis are of curved section inclined atrelatively small angles to the tangentili direction, that is, thedirection of motionof the blades. The blades are of relativelysmallsurface area, `not materially greater in aggregate surface than thedisk area, or net area of the runner passage in a plane normal to theaxis; and to avoid undue surface resistance the impeller is free fromggg shroud ring surrounding theA blades.

i enviewed axially the blades do not overr1113K each other in theportion near their tips.

eimpeller will have a small number of blades, usually between three andsix. For hydraulic reasons the hubs and sleeve 23 must obe unduly small,but should be of substantial diameter. i A

The impeller may have blades extending radially outward from the hub, orslightly inclined to the axis when viewed in a sectionfcontaining theaxis as shown in Fig. 1. In the design shown, the discharge from theportion of the blades near the hub is axial or nearly axial, while thedischarge from the ,'tioni (if the blades near the tips has anoutwardler'adial component, the turning of the waterifrom axial toradial beginning within the `runner. The iows from both runnersconstructed of castings and the entire casing near the hubs are allowedto join and turn from axial to radial along their natural lines of flowaccording to hydrodynamic principles, this turning being produced by anincrease in pressure head and corresponding reduction of velocity headwhere the streams join near the center of the surface of sleeve 23. Byomitting any forced guidance of the fiow as by an enlarged conical bodybetween the runners, surface friction is minimized, the structure ismade compact with the runners close together, and it becomes unnecessaryto support a large central deflecting body, either by carrying it on therotating shaft -or by ribs extending from the fixed casing.

Vhile this invention is illustrated and described more particnariy withreference to hydraulic pumps having a central dischar passage andseparate intake passages it 1s not confined thereto but is intended tocover hydraulic pumps having a central intake passage and separatedischarge passages and any other modifications within the scope of theappended claims.

I claim:

1. A rotary hydraulic pump having in combination two oppositely disposedunshrouded impellers of approximately axial flow ty, a casing having asingle central passage tween said impellers, walls forming the outsideboundary of a transition space and having surfaces of revolutionsmoothly curving from the impeller tips to the casing entrance, and aninside boundary wall of said transition space comprising a sleeve whichis continuous in contour with the impeller hubs, and at nopointmaterially greater in diameter than said impeller hubs.

2.`A rotary hydraulic pump having in combination two oppositely disposedunshrouded impellers of approximately axial How type, a single volutedischarge casin receiving the discharge from both of sai impellers,walls forming the outside boundary of a transition space and havingsurfaces of revolution smoothly curving from the impeller tips to thecasing entrance, and an inside boundary wall of said transition spacecomprising a. sleeve which is continuous in contour with the impellerhubs, and at no point materially greater in diameter than said impellerhubs.

3. A rotary hydraulic pump having in combination two oppositely disposedunshrouded impellers of approximately axial flow type, a singlevolutedischar e casing receiving the discharge from both 0% said impellers andgradually decelerating the velocity of said discharge, walls forming theoutside boundary of a. transition space and having surfaces ofrevolution smoothly curv ing from the impeller tips to the casinentrance, and an inside boundary wall o said transition space comprisinga sleeve which is continuous in contour with the impeller the low fromapproximately axial to a radialr outward direction. v'

4. A vrotary hydraulic pump hav-ing m combination two oppositelydisposed un-V shrouded impellersy of approximately axial flow type, asingle volute discharge casing receiving the'discharge from both of saidimpellers, a common transitionl spacel the walls of'which turn thedischarge from sait Vimpellers from approximately axial to a radialdirection, the discharge from both of said impellers being permitted tomerge freely along a transverse plane midway between said impellerswithout theinterposition of than the outside diameter of either of saidvimpellers.

6. A rotary hydraulic pumpY having'in combination two' oppositelydisposed unshrouded impellers of approximately axial flow type, asinglevolute` discharge Vcasing receiving'the discharge from both ofsaid impellers, and a common transition space, the walls of which turnthe discharge from said impellers from. approximately axial to a radialdirec-tion, the discharge from both of said impellers being permitted tomerge freely along a transverse plane Lmidway between said impellers,said impellers being separated by an axial distance `less than theoutside diameter of either of said impellers.

7 A rotary hydraulic pump havingl in v combina-tion two oppositelvdisposed unshrouded impellers of approximately axial flow type, a singlevolute discharge casing receiving the discharge from both of saidimpellers, and a common transition space, the walls of which turn thedischarge from said impellers from approximatelyn axial to a radialdirection, thev discharge from both of said impellers being permitted tomerge freely along a transverse plane midway between said impellers,said impellersy being spaced 'apart at a relatively small distance andsurrounded by a wall formingV a' surface of revolution converging alonga smooth curve to a minimum diameter at or near the entrance oftheimpeller and then continuously vcurving outward away fromA the' axistoaradial direction at entrance to .thevolute casing. i

Si.V A rotary hydraulic pump having in combination two oppositelydisposed unshroudedimpellersA of axial flow type, and a single volutedischargey casing receiving the discharge from both of said impellers,said' impellers being spaced by a substantially cylindrical sleeve.

9. A rotary hydraulic pump having in combination two oppositely disposedpropeller type impellers secured to the same shaft, and a single volutedischarge casing receiving the discharges from both of said impellers,said impellers being spaced by a cylindrical sleeve secured to saidshaft androtating with said impellers.

l0. In aI double pump the combination with a central volute passage, ofa cylindrical substantially straight sleeve therein, of a runner on eachside thereof, anda plurality of outward passages leading from therunners to the volute passage and discharging therein. 'i

ll. In a twin hydraulic pump a Icentral outlet casingand a pair of inletcasings, said inlet and outlet casings being formed with continuousinlet and outlet passages, a pair of impellers in said passages, a shaftupon which said impellers are mounted, and a substantially straightcylindrical sleeve on said shaft spacing the impellers.

l2. Vln a twin hydraulic pump a central outlet casing and a pair ofinlet casings, said inlet and outlet casings being formed withcontinuous inlet and outlet passages, a pair of impellers in saidpartages, a shaft upon which said impellers are nnuinted7 andsubstantially straight cylindrical sleeve attached to said shaftforspacing the impellers and rotating therewith, and guide vanes in theinlets to said impellers. y

13. ln a double vpump aV c 'ral casing comprisingl an outer wall asubstantially straight cylindrical sleeve, said wall and sleeve formingbetween them a volute discharge passage, annular passages discha ngaxially into said volute, and impellers i said annular passages. v

la. A double pump having a central 'caslng formed of an outer wall, acylindrical sleeve, said wall and sleeve forming between them a volutedischarge passage, annular passages communicating therewith, impellersin said annular passages, a sh t extending through said sleeve andcarrying said impellers. and an intake passage to each impellercontained between an outer converging surface of revolution and an innersurface of revolution coaxi al therewith.

l5. In a hydraulic pump the combinatio with a plurality of unshroudedimpellers of substantially axial flow type, of an impeller casingsurrounding each of said impellers and acentral volutecasing, each ofsaid impeller All i having walls formed as surfaces of revolutionsmoothly curving from axial to radialdirection to form a throat andmerging into the walls of the central volute casing and e through avane-free passage directly utnisaid central volute casing which flaresi'xinllybeyond said throat.

fltphr. a hydraulic piunp thecombination with a central volute casing ofa substantially `egflilldlfoal sleeve within said casing, an imf 0n eachSide of said sleeve, guide vanes in advance of each impeller and aplurality offoutward passages leading from the impellers-to the centralvolute passage and discharging therein.

.17.. In a hydraulic pump the combination with a central volute casing,of a substantial- 1y cylindrical sleeve within said casing, anunshrouded impeller of substantially axial type on each side of saidsleeve, fixed glde vanes in advance of each impeller and a plurality ofoutward passages leading from the impellers to the central volute casingand discharging therein.

18. A rotary hydraulic pump having in combination two oppositelydisposed unshrouded impellers of approximately axial flow type, a singlevolute discharge casing receiving the discharge from both of saidimpellets, and inner and outer walls foi-min a eommon transition spacethe inner wall extendin relatively close and substantially parall to theaxis of the impellers for substantially the entire distancetherebetween, said transverse space turning the discharge from saidimpellers from approximately axial to a radial direction, the dischargefrom Said impellers merging freely between said impellers.

19. A rotary hydraulic pump having in combination two oppositelydisposed unshrouded impellers of approximately axial flow type, a singledischarge casing receiving a discharge from both of said impellers,walls forming the outside boundary of a free transition space havingsurfaces of revolution curving from the impeller tips to the cas-`entrance and an inside boundary wall ot' said transition space formedby a sleeve centinuous in contour with the impeller hubs and smaller indiameter than the diameter of the impellers to permit the flows from theimpellers to freely merge between them.

` 20. In a hydraulic pump the combination with a plurality of unshroudedimpellers of substantially axial How type, of fixed guidevanes inadvance of each impeller, an impeller casing surrounding each of saidimpellers and a central volute casing, each of said impeller casingshavinV walls smoothly curving and merging into tie walls of the centralvolute casing and forming a va ne tree pass-.ige opening directly intosaid central volute 21. rotary hydraulic pump having in combination twooppositely disposed unshrouded impellers of approximately axial flowtype, a casing having a single central passa e between said impellers,walls forming t e outside boundary of a transition space and havingsurfaces of revolution smoothly curving from the impeller tips to thecasing throat, and an inside boundary wall of said transition spacecomprising a sleeve which is continuous in contour with the impellerhubs and at no point materially greater in diameter than said impellerhubs.

22. In a h draulic Pump the combination with a plura ity of impellers ofsubstantially axial low type, of an impeller casing surrounding each ofsaid impellers and a central volute discharge casing, means iorproducing two whirling streams axially progressing toward each other,said impellers rotating in the same direction as the streams and actingupon said streams and discharging said streams toward each other, andmeans whereby the two streams freely merge between said impellers alonga transverse plane midway between said impellers including a wall ofsaid rotating element extending between the hubs of the im ellers, saidwall being everywhere materia ly smaller in diameter than said impellerswhereby a relatively unobstructed axially extending passage is providedbetween said impellers thereby to eilect said free merging.

23. In a h draulic pump the combination with a plurality of impellers ofsubstantially axial fiow type, of an impeller casing surrounding each ofsaid impellers and a central volute casing having a relativelyunobstructed axially extending transition space between saidimpellerslixed guide vanes in advance of said impellers to impart a whirl to thefiow for producing two whirling streams axially progressing toward eachother, said impellers rotating in the same direction as the streams andacting upon said streams and dischargin said streams toward each otherwhereby t e two streams are etliciently merged between said impellersalong a transverse lane midway between said impellers.

24. n a hydraulic pump the combination with a plurality of impellers ofsubst-antiall axial `fiow type, of fixed guide vanos in a vance of eachimpeller, an impeller casing surrounding each of said impellers and acentral volute casing, each of said impeller casings having wallssmoothly curving and merging into the walls of the central volute casingand opening directly into said central volute casing without a centraldeflecting surface, said walls forming a transition space between theguide vanos and impellers, and a second transition space between theimpellers and said central volute casing.

25. A rotary hydraulic pump having in combination two oppositelydisposed axially spaced unshrouded impellers of substantial- Utl lut

llt)

ly axial flow type, an impeller casing surrounding each of saidimpellers and a single central volute casing having a relatively clearaxially extending transition space between said impellers, said spacehaving a radial depth extending for a major portion of the distance fromthe hub to the blade tips, said impellers being of high specilic speedand having a relatively small number of blades, not less than 3, thearea of whichis not materially greater in aggregate surface than thedisk area of the passage in the impeller casing in which the impeller islocated.

26. In a rotary hydraulic pump having in combination two oppositelydisposed unshrouded high speed impellers of substantially axial flowtype provided with a relatively small number of blades not less thanthree, an impeller casing surrounding each impeller, said inipellersbeing spaced apart axially and with a relatively clear transition spacetherebetween said clear space having a radial depth extendingsubstantially from the hub to the blade tips, and a single centralvolute casing, said blades having a relatively small surface areanon-overlapping in the portion near their tips when viewed axially.

27, A rotary hydraulic pump having in combination two oppositelydisposed axially spaced unshrouded high speed impellers of substantiallyaxial liow type, an impeller casing for each impeller and a singlecentral volute casing having a relatively clear axially extendingtransition space between said impellers, said space having a radialdepth extending for a major portion of the distance from the hub to theblade tips, said volute casing also having a throat less thanthreefourths of the greatest diameter of the impellers in order toconform to the flow, each of said impeller casings having walls smoothlycurving and merging into the walls of the central volute casing.

LEWIS FERRY MOODY.

